'use strict';

/* eslint no-invalid-this: 1 */

var ERROR_MESSAGE = 'Function.prototype.bind called on incompatible ';
var toStr = Object.prototype.toString;
var max = Math.max;
var funcType = '[object Function]';

var concatty = function concatty(a, b) {
 var arr = [];

 for (var i = 0; i < a.length; i += 1) {
 arr[i] = a[i];
 }
 for (var j = 0; j < b.length; j += 1) {
 arr[j + a.length] = b[j];
 }

 return arr;
};

var slicy = function slicy(arrLike, offset) {
 var arr = [];
 for (var i = offset || 0, j = 0; i < arrLike.length; i += 1, j += 1) {
 arr[j] = arrLike[i];
 }
 return arr;
};

var joiny = function (arr, joiner) {
 var str = '';
 for (var i = 0; i < arr.length; i += 1) {
 str += arr[i];
 if (i + 1 < arr.length) {
 str += joiner;
 }
 }
 return str;
};

module.exports = function bind(that) {
 var target = this;
 if (typeof target !== 'function' || toStr.apply(target) !== funcType) {
 throw new TypeError(ERROR_MESSAGE + target);
 }
 var args = slicy(arguments, 1);

 var bound;
 var binder = function () {
 if (this instanceof bound) {
 var result = target.apply(
 this,
 concatty(args, arguments)
 );
 if (Object(result) === result) {
 return result;
 }
 return this;
 }
 return target.apply(
 that,
 concatty(args, arguments)
 );

 };

 var boundLength = max(0, target.length - args.length);
 var boundArgs = [];
 for (var i = 0; i < boundLength; i++) {
 boundArgs[i] = '$' + i;
 }

 bound = Function('binder', 'return function (' + joiny(boundArgs, ',') + '){ return binder.apply(this,arguments); }')(binder);

 if (target.prototype) {
 var Empty = function Empty() {};
 Empty.prototype = target.prototype;
 bound.prototype = new Empty();
 Empty.prototype = null;
 }

 return bound;
};